Pan-cancer analysis of the prognostic significance and oncogenic role of GXYLT2

Growing evidence supports an oncogenic role for glucoside xylosyltransferase 2 (GXYLT2) in a number of malignancies. To evaluate the prognostic value and oncogenic function of GXYLT2 in diverse cancer types, we analyzed sequencing data from public databases on 33 tumor tissues and their corresponding normal tissues. We found that GXYLT2 was overexpressed in a number of tumors, and that its expression was positively correlated with disease progression and mortality in several major cancer types including stomach adenocarcinoma (STAD). GXYLT2 was also linked to tumor size, grade, and the immune and molecular subtypes of STAD. GO and KEGG pathway analyses of GXYLT2 co-expressed genes in STAD suggested that GXYLT2 possibly plays a role in epithelial-mesenchymal transition, extracellular matrix production and degradation, angiogenesis, apoptosis, as well as in tumor inflammation, such as cytokine production and T cell activation. Finally, prognostic nomograms were created and validated for predicting 1, 3, and 5-year survival of patients with STAD. Our findings indicate that GXYLT2 may play a role in tumorigenesis and tumor immunity, and it may serve as a prognostic marker and potential immunotherapeutic target for STAD and some other types of cancer.

The expression and biological information analysis of miR-375-3p in head and neck squamous cell carcinoma based on 1825 samples from GEO, TCGA, and peer-reviewed publications

BACKGROUND

The specific expression level and clinical significance of miR-375-3p in HNSCC had not been fully stated, as well as the overall biological function and molecular mechanisms. Therefore, we purpose to carry out a comprehensive meta-analysis to further explore the clinical significance and potential function mechanism of miR-375-3p in HNSCC.

METHODS

HNSCC-related data was gained from Gene Expression Omnibus (GEO), The Cancer Genome Atlas (TCGA), and peer-reviewed journals. A meta-analysis was carried out to comprehensively explore the relationship between miR-375-3p expression level and clinicopathological features of HNSCC. And summary receiver operating characteristic (SROC) curve analysis was applied for evaluating disease diagnosis value of miR-375-3p. In addition, a biological pathway analysis was also performed to assess the possible molecular mechanism of miR-375-3p in HNSCC.

RESULTS

A total of 24 available records and references were added into analysis. The overall pooled meta-analysis outcome revealed a relatively lower expression level of miR-375-3p in HNSCC specimens than that in non-cancerous controls (P < 0.001). And SROC curve analysis showed that the pooled area under the SROC curve (AUC) was 0.90 (95%CI: 0.88-0.93). In addition, biological pathway analysis indicated that LAMC1, EDIL3, FN1, VEGFA, IGF2BP2, and IGF2BP3 maybe the latent target genes of miR-375-3p, which were greatly enriched in the pathways of beta3 integrin cell surface interactions and the binding of RNA via the insulin-like growth factor-2 mRNA-binding protein (IGF2BPs/IMPs/VICKZs).

CONCLUSION

MiR-375-3p expression clearly decreased in HNSCC samples compared with non-cancerous controls. Meanwhile, miR-375-3p may serve as a tumor suppressor via regulating tumor-related genes LAMC1, EDIL3, FN1, VEGFA, IGF2BP2, and IGF2BP3 in HNSCC.

Decreased expression of ING2 gene and its clinicopathological significance in Chinese NSCLC patients

The inhibitor of growth 2 (ING2) is a member of lNG family, involved in cell cycle regulation, DNA repair, apoptosis and senescence, and participating in chromatin remodeling and transcriptional regulation by histone modification. Recent researches suggest ING2 plays roles in carcinogenesis both as tumor suppressor gene and ongocene depending on tumor types and cell status. Here, we investigated the status of ING2 in a series of 64 Chinese non-small cell lung cancer (NSCLC)patients using immunohistochemistry (IHC) and confirmed the results with Western blotting. RT-PCR results revealed the expression level of ING2 was consistent with mRNA level. The IHC results showed that ING2 protein expression was significantly decreased in NSCLC samples compared with normal lung tissues (P<O.OS). ING2 expression was lost in 32.8%(21/64) NSCLC tissues, which was more frequently in adenocarcinoma (ADK) than in squamous cell carcinoma (SCC), 45.8%(11124) and 26.3% (10/38), respectively. We also found ING2 translocation from the nucleus to the cytoplasm, which may bea critical event for carcinogenesis. And the status of ING2 in SCC was significantly associated with lymph node metastasis status and TNM stage. After sequencing ING2 gene, we found no heterozygosity or mutation. Taken together, these results indicated that the aberrantly expression of ING2 may contribute to NSCLC tumorigenesis.

A new Hansenula polymorpha HAP4 homologue which contains only the N-terminal conserved domain of the protein is fully functional in Saccharomyces cerevisiae

In Saccharomyces cerevisiae, the HAP transcriptional complex is involved in the fermentation-respiration shift. This complex is composed of four subunits. Three subunits are necessary for DNA-binding, whereas the Hap4p subunit, glucose-repressed, contains the transcriptional activation domain. Hap4p is the key regulator of the complex activity in response to carbon sources in S. cerevisiae. To date, no HAP4 homologue has been identified, except in Kluyveromyces lactis. Examination of these two HAP4 sequences led to the identification of two very short conserved peptides also identified in other yeasts. In the yeast Hansenula polymorpha, two possible HAP4 homologues have been found. Their deduced amino acid sequences are similar to the ScHap4p and KlHap4p proteins only in the N-terminal 16-amino-acid basic motif. Since molecular genetic tools exist and complete genome sequence is known for this yeast, we expressed one of these putative HpHap4 proteins in S. cerevisiae and showed that this protein is able to restore the growth defect of the S. cerevisiae hap4-deleted strain. A set of experiments was performed to confirm the functional homology of this new gene with ScHAP4. The discovery of a Hap4-regulatory protein in H. polymorpha with only the N-terminal conserved domain of the S. cerevisiae protein indicates that this domain may play a crucial role during evolution.

Secretion of human proteins from yeast: stimulation by duplication of polyubiquitin and protein disulfide isomerase genes in Kluyveromyces lactis

The efficiency of secreted production of mammalian proteins from yeasts remains unpredictably variable, depending on each protein. On the hypothesis that the control of protein conformation during protein translocation is the bottleneck in many cases, we examined the effects of an increased dosage of the genes coding for protein disulfide isomerase and of polyubiquitin on the secretion of two human proteins, serumalbumin and interleukin 1 beta. The yeast Kluyveromyces lactis was used as a production host. Duplication of either one of these genes had a strong stimulating effect on the production of the highly disulfide-bonded serumalbumin, but not of interleukin 1 beta.

The ubiquitin-encoding genes of Kluyveromyces lactis

The ubiquitin encoding genes of Kluyveromyces lactis were cloned. Three genes, KlUBI1, KlUBI3 and KlUBI4, were found in this yeast, while in Saccharomyces cerevisiae there are four genes, UBI1, -2, -3 and -4. The UBI1/UBI2 duplication is thus absent from the K. lactis genome. General structural features of ubiquitin genes were very similar in these two species (presence of an intron in KlUBI1, fusion to ribosomal protein genes in KlUBI1 and KlUBI3, spacer-less polyubiquitin repeats in KlUBI4). Disruption or deletion of K. lactis ubiquitin genes showed that: (a) disruption of KlUBI1 was lethal (in S. cerevisiae, ubi1/ubi2 double deletion is lethal); (b) KlUBI3 is also an essential gene for cell growth; (c) deletion of KlUBI4 led to an increased sensitivity to high temperature, similar to the ubi4 mutation in S. cerevisiae, but, in contrast to the latter, the klubi4 mutant was not sensitive to carbon or nitrogen source starvation. The syntenic relationship of ubiquitin loci between K. lactis and S. cerevisiae genomes is also described.

Protein disulphide isomerase genes of Kluyveromyces lactis

Two genes of Kluyveromyces lactis, KlPDI1 and KlMPD1, were studied. They code for a protein disulphide isomerase and its structural and functional homologue, respectively. The KlPDI1 product was 52.6% identical to Pdi1p and the KlMPD1 product 47% identical to Mpd1p of S. cerevisiae. Both genes contained the thioredoxin-active site-related signature. Their C-termini showed a new variant of the endoplasmic reticulum-retention signal, QDEL. A single copy of KlPDI1 was able to complement the growth defect of a pdi1 mutation. KlMPD1 on a multicopy vector partially suppressed the klpdi1 and pdi1 mutations. The Klpdi1 null mutation was lethal. The klmpd1 disruptant was viable, but showed an increased sensitivity to high temperature. Several stress response motifs were present in the upstream sequence of KlMPD1, but not of KlPDI1, whilst the opposite is known for the S. cerevisiae homologues. The viability of the klmpd1 mutant under starvation for nitrogen or carbon source was not different from that of the wild-type. The syntenic relationship is discussed for the KlPDI1 gene regions with respect to the duplicated segments PDI1/EUG1 in S. cerevisiae.

Disruption of the MRP-L23 gene encoding the mitochondrial ribosomal protein L23 is lethal for Kluyveromyces lactis but not for Saccharomyces cerevisiae

The Kluyveromyces lactis nuclear gene, MRP-L23, encodes a polypeptide of 155 amino acids that shares 70% and 43% identity to the ribosomal proteins L23 and L13 of Saccharomyces cerevisiae and Escherichia coli. The deduced protein, designated K1L23, is a likely component of the large subunit of mitochondrial ribosomes as it can complement the respiratory deficient phenotype of a S. cerevisiae mrp-L23 mutant. As in S. cerevisiae, KlMRP-L23 is essential for respiratory growth of K. lactis because disruption of the gene in a "petite-positive" strain carrying a rho o-lethality suppressor atp mutation rendered cells unable to grow on a nonfermentable carbon source. However, in contrast to S. cerevisiae, disruption of MRP-L23 in wild type K. lactis is lethal. Meiotic segregants of K. lactis with a disrupted MRP-L23 allele form microcolonies with cell numbers varying from 32 to 300. These data clearly indicate an essential role of mitochondrial protein synthesis for viability of the petite-negative yeast K. lactis.